It was formed on mobilisation in August 1914 from the VI Army Inspection.

The 4th Army defeated Belgian forces on the frontier, drove the French out of the Ardennes and then encountered the British Expeditionary Force in the "Race to the Sea" at the First Battle of Ypres.

The 4th Army faced the British in Flanders for the rest of the war, notably defending in the Battle of Passchendaele (1917), attacking in the 1918 German spring offensive and finally being pushed back in the Hundred Days Offensive from August 1918.

At the end of the war it was serving as part of Heeresgruppe Kronprinz Rupprecht.

[5] The later World War II-era Wehrmacht general Heinz Guderian served as an assistant signals officer (initially as a lieutenant) at 4th Army HQ until his reassignment to the German general staff in 1918.